When my daughter had just turned 7, she asked for us to build a puzzle box that only she could open. She drew up her projections here:
That was almost 4 years ago. We brainstormed, tweaked designed (and re-designed) a puzzle box together and finally produced this:
Here’s the youtube walkthrough on how to open it
We learned so many new techniques. Almost exclusively built with our glowforge and 3d printer (Zortrax m200).
Lots of fun!